1. Field of the Invention
The present invention relates to an optical zoom lens, and more particularly to a miniature zoom lens which has at least one driving coil generating an electromagnetic force interacting with at least one permanent magnet of at least one lens assembly so as to actuate the lens assembly to linearly move relative to a guiding rod for adjusting the focus of at least one lens unit on the lens assembly.
2. Description of the Prior Art
Referring now to FIG. 1, a mechanically actuated zoom mechanism 90 used in a conventional camera device is illustrated, which is provided with a precise driving unit 91 with high manufacturing cost (for ex., stepping motor, ultrasonic motor, piezoelectric switch, and etc.), a lens unit 92, a supporting base 93 supporting the lens unit 92 and actuated by the precise driving unit 91, and other driving elements so as to complicate the entire structure of the conventional camera device and the assembling steps thereof while being disadvantageous to reduce the volume, the manufacturing cost, and the power consumption thereof.
In early stages, conventional photographic technologies were very complicated, and only provided manual functions for manually metering, zooming, and film-winding so as to create problems in imprecision. Especially, during an important occasion, if the conventional photographic technologies only take an unclear picture of an important view, the important view might passed away and not be taken another clear picture again so that the experience of a photographer is important to the quality of photograph. In the 1950's and 1960's, mechanical automation of photographic technology was developed, and more and more people believe that automation thereof is a future trend of development and research in the photographic field. The originally developed technologies of automatically metering and film-winding are evidence for automation of photographic technology, wherein a key for accelerating the velocity of a camera shutter is an “automatic zoom system” which plays a critical role in development and research of the photographic industry.
As photographic technology advanced, the conventional camera device is improved to provide a novel product with higher resolution and more compact volume for fulfilling requirements of customers in the modern information society. However, a mechanical zoom lens actuated by a stepping motor has a larger volume which can not be further reduced to become a more compact volume so as to cause a limit to improve the mechanical zoom lens. In another aspect, an electromagnetic technology is developed, and it provides an electrically feedback control system to control the offset of a voice coil motor (VCM) which is a more compact actuator used to replace the conventional stepping motor. Furthermore, various electrical mechanisms having different functions are integrated into a unit. For example, a photographic mechanism is selectively integrated into a mobile phone with a telecommunicating function, a personal digital assistant (PDA), or a notebook computer so that the mobile phone, the PDA, or the notebook computer will be able to further provide a photographic function. Thereby, when the integrated mechanisms as described above are mounted in a common device using a common power supply, it is important to develop how to reduce the entire volume, the manufacturing cost, and the power consumption thereof so as to be advantageous to increase the standby time and the communicating time of the integrated mechanisms if mounted in the same device using the same power supply of equal capacity. It is therefore tried by the inventor to develop a miniature zoom lens to solve the problems existed in the conventional mechanically optical zoom lens.